Cardiac Sarcomere Protein Quality Control in Health and Disease

健康和疾病中的心脏肌节蛋白质量控制

• 批准号: 10621229
• 负责人: JONATHAN A KIRK
• 金额: $ 53.92万
• 依托单位: LOYOLA UNIVERSITY CHICAGO
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-04-01 至 2027-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10621229
• 关键词: Actins; Autophagosome; BAG3 gene; Binding; Biological Assay; Biophysics; Cardiac; Cardiac Myocytes; Cells; Client; Complex; Data; Depressed mood; Disease; Functional disorder; Future; Generations; Grant; Half-Life; Health; Heart; Heart failure; Heat-Shock Proteins 70; Heat-Shock Response; Human; Impairment; In Vitro; Knockout Mice; Knowledge; Lasers; Lysosomes; Mechanical Stress; Mediating; Mental Depression; Methods; Modeling; Modification; Molecular Chaperones; Mus; Muscle Cells; Myocardial Infarction; Myosin ATPase; Nature; Neonatal; Pathway interactions; Patients; Phenotype; Process; Proteins; Publishing; Quality Control; Rattus; Regulation; Relaxation; Role; Sarcomeres; Sedimentation process; Signal Transduction; Stimulus; Stress; Structure; System; Therapeutic; Transgenic Mice; Tropomyosin; Ubiquitin; Ubiquitination; Ventricular; Visualization; Work; cell motility; cost; gene therapy; improved; in vivo; induced pluripotent stem cell; live cell imaging; misfolded protein; new therapeutic target; protein degradation; protein protein interaction; proteotoxicity; recruit; response; spatiotemporal; ubiquitin isopeptidase; ubiquitin ligase; ultra high resolution

Cardiomyocytes are essentially non-renewing, so proteotoxicity from dysregulated Protein Quality Control (PQC) is intimately associated with heart failure. The proteins that comprise the cardiac sarcomere are responsible for force generation in the myocyte, and this constant mechanical stress uniquely predisposes them to misfolding. Despite PQC’s central role in heart failure, and the particular vulnerability of the sarcomere to misfolding, the PQC mechanisms that maintain the cardiac sarcomere are almost entirely unknown. This is a critical knowledge gap that we will address in this proposal. Our past work described a z-disc localized complex, anchored by the co- chaperone Bcl2-associated athanogene-3 (BAG3), that was essential for sarcomere PQC. Z-disc BAG3 levels were depressed in human heart failure (HF) and correlated with decreased sarcomeric force-generating capacity (Fmax). Similarly, cardio-myocyte specific inducible BAG3 KO mice had increased ubiquitination of sarcomeric proteins that remained integrated in the lattice, reducing force generation. Importantly, BAG3 gene therapy in a mouse HF model reversed this phenotype, indicating the potential of targeting sarcomere PQC to improve contractile function. In this renewal we will address the central hypothesis that sarcomere PQC occurs via sarcomere-localized pathways and depression of these systems in HF due to BAG3 instability results in accumulation of ubiquitinated proteins that induce dysfunction. In Aim 1 we will Explore the spatiotemporal organization of the key steps in sarcomere PQC. We will use super-resolution live cell imaging in neonatal rat ventricular myocytes (NRVMs) and human iPSC-CMs to visualize the spatiotemporal interplay between BAG3, autophagosomes, lysosomes, the z-disc, and BAG3-clients at baseline and in response to various stress and stimuli, such as heat shock, localized laser damage, hypertrophic signaling, and depressed BAG3 levels. In Aim 2 we will identify the functional consequences of sarcomeric protein ubiquitination. We will use in vivo and in vitro approaches to modulate sarcomere protein ubiquitination and assess the impact on sarcomere function with biophysical assays (force- Ca2+ relationship, tension cost, in vitro motility assay, super-relaxed state, co-sedimentation). In Aim 3 we will discover the regulation of BAG3 in the cardiomyocyte and how it is altered in heart failure. We will use several transgenic mouse lines and a myocardial infarction induced heart failure model, to discover the interplay between HSP70, BAG3, heart failure, and sarcomere PQC. We expect to identify new methods to stabilize BAG3 in the failing heart as a possible therapeutic strategy. These 3 aims establish a foundational understanding of sarcomere PQC, functional consequences of its misregulation, and how it can be modulated in vivo.

心肌细胞本质上是不可更新的，因此失调的蛋白质会产生蛋白质毒性 质量控制（PQC）与心力衰竭密切相关。组成的蛋白质 心脏肌节负责在肌细胞中产生力，并且这种恒定的机械力 压力特别容易导致它们错误折叠。尽管 PQC 在心力衰竭中发挥着核心作用，并且 肌节特别容易发生错误折叠，维持 心脏肌节几乎完全未知。这是一个关键的知识差距，我们将 本提案中的地址。我们过去的工作描述了一个 z 盘局部复合体，由共同锚定 Bcl2 相关伴侣 athanogene-3 (BAG3)，对于肌节 PQC 至关重要。 Z盘 BAG3 水平在人类心力衰竭 (HF) 中降低，并与肌节减少相关 产生力的能力（Fmax）。同样，心肌细胞特异性诱导的 BAG3 KO 小鼠也具有 保持整合在晶格中的肌节蛋白的泛素化增加，减少了力 一代。重要的是，小鼠心衰模型中的 BAG3 基因治疗逆转了这种表型， 表明靶向肌节 PQC 改善收缩功能的潜力。在这次更新中我们 将解决肌节 PQC 通过肌节局部途径发生的中心假设 由于 BAG3 不稳定，HF 中这些系统的抑制会导致 引起功能障碍的泛素化蛋白质。在目标 1 中，我们将探索时空 肌节 PQC 关键步骤的组织。我们将使用超分辨率活细胞成像 新生大鼠心室肌细胞 (NRVM) 和人类 iPSC-CM 以可视化时空 BAG3、自噬体、溶酶体、z 盘和 BAG3 客户端之间在基线和 响应各种压力和刺激，如热休克、局部激光损伤、肥大 信号传导，并降低 BAG3 水平。在目标 2 中，我们将确定以下功能的后果 肌节蛋白泛素化。我们将使用体内和体外方法来调节肌节 蛋白质泛素化并通过生物物理测定（力- Ca2+ 关系、张力成本、体外运动测定、超松弛状态、共沉降）。瞄准 3 我们将发现 BAG3 在心肌细胞中的调节以及它在心力衰竭中如何改变。 我们将使用几种转基因小鼠品系和心肌梗塞诱发的心力衰竭模型， 发现 HSP70、BAG3、心力衰竭和肌节 PQC 之间的相互作用。我们期望 确定稳定衰竭心脏中 BAG3 的新方法作为可能的治疗策略。这3个 目的是建立对肌节 PQC 及其功能后果的基本了解 失调，以及如何在体内调节它。